How Touch Screens Work

Your phone screen reacts to the lightest brush of your finger and

ignores a pen pressed as hard as you can.

So what is it actually feeling? It isn't really feeling pressure.

It's measuring the electricity in your body.

Imagine it's winter and you're trying to answer a call with

your gloves on.

Under the glass of your phone, there's a grid of wires you can't see,

rows

going one way and columns going the other.

Everywhere a row crosses a column, the phone holds a tiny electric

charge, and it checks every one of those crossings

over and over.

Your body is mostly salty water, so it conducts electricity.

When your bare fingertip gets close to the glass, it pulls a little of that

charge away from the crossings right under it.

The phone sees a small dip at those exact crossings and says, "That's a

touch." And because it measures every crossing separately, it can follow two

fingers at once, which is how you pinch to zoom.

But your glove doesn't conduct anything, so your finger is right there pressing on

the glass and the charge never moves.

For the phone, nobody touched it. That's also why your screen goes crazy in

the rain. Water conducts too, so every drop looks like a finger.

And it's why touch screen gloves work.

They have a thread in the fingertips that conducts, and it carries your body's

electricity to the glass. So your screen never felt your finger.

It felt a tiny bit of charge go missing, and your finger was just the thing

that took it. Follow me and send this to someone whose phone never

works

with wet hands.